Difficulties in flotation separation of copper, lead and zinc

Iron, copper and zinc are the first, third and fourth most consumed metals in the world, and are indispensable raw materials for the automotive, aviation, construction, machinery, shipbuilding and other industries. With the continuous development of the national economy, the consumption of copper, zinc and iron mineral resources has increased rapidly. In my country, copper, zinc and iron mainly exist in the form of complex polymetallic ores. Therefore, the comprehensive utilization of copper, zinc and iron polymetallic ores is of great significance.

The common method for separating iron minerals from copper and zinc sulfide minerals is magnetic separation, while flotation is the most common method for enriching copper and zinc. Therefore, the flotation-magnetic separation combined process is often used to separate and enrich copper, zinc and iron from polymetallic ores. However, it is still very difficult to achieve complete separation of copper and zinc by flotation. The main reasons are as follows:

(a) Copper and zinc minerals are closely interwoven, and it is difficult for copper and zinc mineral monomers to dissociate;

(b) During the grinding process, copper ions in the slurry are adsorbed on the surface of sphalerite, resulting in sphalerite having similar floatability to chalcopyrite;

(c) Copper and zinc sulfide minerals are easily oxidized, resulting in poor floatability. Formulating a reasonable mineral processing process and selecting a suitable reagent system based on the characteristics of the ore are the key to separating copper and zinc sulfide minerals.

The main flotation separation processes for copper and zinc sulfide minerals include differential flotation, mixed flotation and equal flotation.

Mixed flotation

The characteristic of mixed flotation is that after the first grinding, as many copper and zinc sulfide minerals as possible float to the surface together. The mixed concentrate is re-ground and further separated by flotation. The disadvantage of this process is that the mixed concentrate contains too much reagent, which makes subsequent mineral separation difficult.

Isoflotation

Isoflotation is characterized by simultaneously flotating copper sulfide minerals with good floatability and some zinc sulfide minerals, separating the copper and zinc minerals in the mixed concentrate after regrinding, and flotating the zinc minerals with poor floatability in the tailings separately, so this process is relatively complicated.

Differential flotation

Differential flotation can first float copper minerals, and then float zinc minerals from copper tailings, but it has high requirements for the selectivity of copper collectors. In industry, the process is simple, and the high selectivity of collector Z-200 (O-isopropyl-N-ethylthiocarbamate) makes it widely used